49ers’ Michael Crabtree to return soon

Unless a different injury pops up before the regular-season opener, it appears as if sidelined 49ers wide receiver Michael Crabtree will break his 0-for-the-preseason streak this summer.

On Friday, Jim Harbaugh said Crabtree’s lower-leg injury wasn’t serious and he expects him to return to practice soon. Crabtree, who missed his sixth straight day of practice, ran a series of sprints on an adjacent field as part of his rehab work.

The 49ers open the preseason Friday against the visiting Vikings. Due to a contract holdout and injuries, Crabtree didn’t play in a preseason game in his first three seasons.

“The thing I feel for Michael, I know he’s feeling it, too – he came in such great shape. He looked fantastic,” Harbaugh said. “We feel like we’ll get him back soon and we can pick right up. I don’t think this is going to be a major bump in the road. I think this is going to be a minor one. He’s chomping at the bit to get back out there, and I anticipate that happening soon.”

Defense dominates: The 49ers’ three-hour practice ended, fittingly, with Alex Smith throwing a short pass that was tipped by cornerback Tarell Brown and intercepted by safety Dashon Goldson.

Harbaugh acknowledged the defense dominated the offense “about every which way it could be dominated.”

Defensive tackle Justin Smith played a starring role, deflecting a pass, registering a touch sack and collecting several pressures.

“(Defensive coordinator) Vic Fangio made the comment that this is a great player,” Harbaugh said of Justin Smith. “This is a strong man who plays with incredible leverage, but he plays like a guy who’s fighting to make the roster. That’s a special combination, a rare combination.”

Briefly: Left guard Mike Iupati didn’t practice due to the impending birth of his first child. … Tight end Nate Byham did not practice due to an undisclosed injury. Byham missed last season with an ACL injury he suffered in training camp. … Rookie guard Joe Looney practiced for the first time since he was activated from the non-football injury list Tuesday. … Harbaugh wore a microphone during practice for NFL Films. Per league rules, NFL coaches must wear a microphone during one training-camp practice and one regular-season game.